fix(security): add CSRF protection to all POST endpoints + contract tests (B2)

CSRF guards added to 16 admin pages that previously accepted POST requests
without token verification (GR-SEC-001): departments, permissions, roles,
settings, tenants, users (create/edit/bulk/tokens), and lang switch.

New contract tests:
- PostEndpointCsrfContractTest: scans all pages/ for POST handlers and
  verifies checkCsrfToken is present (API/data endpoints exempt).
- DatabaseUpdatesContractTest: validates db/updates/ scripts follow naming
  convention and use idempotent SQL patterns (GR-CORE-010).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pages/admin/users/access-pdf-bulk().php

@@ -4,6 +4,8 @@ use MintyPHP\Http\SessionStoreInterface;
 use MintyPHP\Router;
 use MintyPHP\Service\Access\UserAuthorizationPolicy;
 use MintyPHP\Service\User\UserAccessPdfService;
+use MintyPHP\Session;
+use MintyPHP\Support\Flash;
 use MintyPHP\Support\Guard;
 
 $session = app(SessionStoreInterface::class)->all();
@@ -27,6 +29,12 @@ if (strtoupper((string) (requestInput()->method())) !== 'POST') {
     return;
 }
 
+if (!Session::checkCsrfToken()) {
+    Flash::error(t('Form expired, please try again'), 'admin/users', 'csrf_expired');
+    Router::redirect('admin/users');
+    return;
+}
+
 $errorBag = formErrors();
 $raw = requestInput()->bodyAll()['uuids'] ?? '';
 $uuids = [];